SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df585ae846ef8e60ed6c993fc4b9503cf4e2cd5b3a117026ede685d4384674bc' 
  AND token = 'zQdEIgJy8BrsWELjN/Zvjlh+rsTpQidHt7tfMYAKSM4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}